1. Field of the Invention
This invention relates a silicone rubber having an improved self-extinguishing property.
2. Description of the Prior Art
Although silicone elastomers exhibit various excellent properties, they are inflammable and attempts have been made to make them self-extinguishable by various methods. For example, a platinum-containing material has been added to silicone rubber compounds as shown by U.S. Pat. No. 3,514,424, issued May 26, 1970, to Noble et al., a platinum compound and (FeO).sub.x (Fe.sub.2 O.sub.3).sub.y where the ratio of x/y is from 0.05/1 to 1.0/1 have been added to silicone rubber compounds as shown by Japanese Pat. No. Sho 51(1976)-35501, published Oct. 2, 1976, to Hatanaka et al. and a platinum compound and .gamma.-type iron sesquioxide have been added to silicone rubber compounds as shown by Japanese Pat. No. Sho 53(1978)-44501. It is known from U.S. Pat. No. 3,965,065, issued June 22, 1976, to Elliott, to make silicone rubber containing aluminum hydrate and a combination of aluminum hydrate and chloroplatinic acid hexahydrate.
As pointed out in the above paragraph, platinum or a platinum compound is an indispensable additive for self-extinguishing silicone rubber compositions and imparts a relatively strong self-extinguishing capacity to silicone rubbers. However, platinum or platinum compounds are very expensive so that the cost of production of the silicone rubber is high. The presence of platinum or a platinum compound adversely affects the heat-stability property of silicone rubber. These are the drawbacks of the self-extinguishing silicone rubbers produced by the methods using platinum or platinum compounds.